Johannes karl ruths



J. K. RUTHS.

PRESSURE LOCK FOR. DIGESTERS.

APPLICATION man no.4. 1919.

1,419,763. Patented June 13, 1922.

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UNITED STATES PATENT OFFICE;

JOI-IANNES KARL RUTHS, OF DJ'URSI-IOLM, SWEDEN, ASSIGN'OR 'IO AKTIEBOLAGET VAPORACKUMULATOR, OF STOOKHOLM, SWEDEN, A CORPORATION.

rnnssunr. LOCK ron DIGESTERS.

Specification of Letters Patent. P t ted June 13, 1922.

Application filed December 4, 1919. Serial No. 342,474.

To all whom it may concern Be it known that I, J OHANNES KARL Burns, Dr.-engineer, subject of the King of Sweden, residingat Djursholm, in the Kingdom of Sweden, have invented certain new and useful Improvements in Pressure Looks for Digesters, of which the following is a specification.

When carrying out digesting processes, for instance in boiling wood splinters in sulphite boilers, it often happens that the pressure of the steam conduit sinks below the pressure prevailing in the'digester, so that part of the acid may be forced back into the steam conduit. This may for} instance be the case where steam is taken in great quantities to be used for steaming purposes, or to start another digester. It may also happen that the valve in the steam pipe immediately before the digester is untight, or that it stands open for the time being, thus causing acid to flow back at a direct boiling. In indirect boiling, the tubes or tube coils may be 'untight so that acid can flow into the conduit.

Lye or acid finding its way into the piping system in the manner described will in such plants often give rise to great difficulties .and drawbacks, the acid corroding the pipes and often getting'even into the boilers, or into an accumulator, steam turbine or the like which may be connected to the piping. Obviously, the various apparatus are in such protect the pipes by making same of acidproof material in spite of the high costs, as

far as this has been possible. In certain other cases endeavours have been made to overcome the drawbacksby arranging apparatus in the conduits to give asi al'atthe v moment when acid entered the piping, so

that the latter could then be shut off,

The. present invention. has for its purpose to obviate these inconveniences by means fully protecting the apparatus connected to the pipings, or the pipings themselves,

against corrosion by the action of escaping: acid, without any particular signalling de-' vices having to be resorted to. At the same time the great advantage isobtained that the valves of the conduit'are kept entirelyflfree from acid, whereby the durability'of the valves is greatly increased, and the maintenance expenditures correspondingly lowered,

pressure in the digester" rises considerably faster, owing to the" gases developed, than corresponding tothe temperature of the contents of the digester, and therefore the starting of the digester up to 100 C. for instance in sulphite boiling could be easily effected at a lower pressure, forv example 1 kilogramme overpressure, but for the risk of getting acid 'into the piping through untight boiling tubes. By the present invention this part of the boiling process is facilitated so that it can be carried out at a considerably lowerpressure, which evidently is of particular importance where counter pressure power is to be'generated in the boiling steam.

Likewise, by the use of the present invention, the steaming in a sulphite boiling plant maybe effected at a pressure but a little exceeding the atmospheric pressure, and hereby certain advantageswill also be attained.

The invention is characterized by the arrangement of a pressure lock in the steam piping near the digester, immediately beside cases subject to serious break-downs; in many cases endeavour-shave beenmade to the acid-proof cut-off valve, the said pressure lock consisting of a short piece of acidproof piping, behind which is disposed a valve, preferably. a non-return valve opening *towards the digester. Between these two valves,preferably as closely as possible to the latter one, a pressure medium, such as steam, water under pressure, air or the like is introduced into the piping, the said medium" 'always'having a pressure exceeding the maximum pressure of the digester. Preferably, steam is used for this purpose, and the maximum quantity of steam flowlng to the place in question is checked by a small valve, a. pressure flange or the like, and selected solarge asto surely exceed that quantity' of steam, which were likely to flow out 'in'case of aleakage occurring in the nonreturn valve 'or the acid-proof valve respectively. In most cases it will be found suitable also to arrange the acid-proof piping between the two valves in the form of a liquid seal, preferably in such manner that the part most remote from the digester is bent upwardly.

In certain cases it may haplppn thatsteam of higher pressure than the imme pressure of the digester is not always available: This is for instance the case Where the boiler pressure exceeds the pressure of the digester only a little. In such cases it often happens" that in starting or steamin a ester, the pressure of the boilers an sink. "elow the res sur e prevailing in one or other of the digesters whereby acid may he forced hack into the piping. such cases there ranged according to th inven-tion a smaller, insulated rece tacle which is to the most part thereof fil ed with water, and into which steam is introduced from the boilers a non-return valve opening'tdwards thereceptacle. Practically the receptacle has always a steam pressure corresponding" to the maximum boiler pressure, and charged only very slewlf through that small quantity of steam whic is apt to leak out through the pressure lock.

This receptacle thus represents a steam accumulator from the top portion of which steam is taken to the pressure lock or the locks respectively.

The invention is ill g V I companying drawin ig..1 showin the pressure lock, and ig, the. accumuator.

In Fig. 1, K denotes the digester, S the acid-proof lining, A the acid-proof cutroif valve, T the pressure lock, and B the nonreturn valve which is connectedto the steam piping L. V a permanent adjusted valve in the narrow steam pipe in which always prevails a h' her pressure. I he cut-off valve A and the pressure block T are, as mentioned above, made of acid-proof metal, whereas, the valve V, the pipings L and M as wales the non-return valve B can be made or metal which is not acidproof. From the valve A steam may flow either directly into the di ester, as indicated in 1, or thesaid igester as be connected with heat coils means of w "ich the contents of th, digester is heated.

The operation pf the plant is as folldws Assuming that the valves A and B are stated in the acperfectly tight and dead at the time heing, then the same. steam pressure prevails in the pressure lock T as 1n the "ipia M. If the valve A is new opened, t is seam pressure will soon be equalized, and in the course of the boilin process a small quantity of steam will how all the. time from the pipe M to ether with the large quantity of steam t rough L into the boiler K.v

Supposing now that during this the steam pressure in the pi e sir ik's below the pressure prevailing rhr the oment in the digester acid wil immedia y force its way from t e digestei through the valve A and into the pressure lock T, the nonreturn valve B being then closed, and now the steam flowing through the pipe M prevents the acid from rising in the pressure lock T. The quantity of steam flowing forth from the conduit M will by degrees force the acid back from the pressure lock T, until theacid has settled along the line I-l- H. Thus it will be understood that the valve B or pipings or apparatus located in front of it never come in contact with the acid. Conditions will be the same should the" valve A not be perfectly tight.

In most cases the conduit M is led from the steam boiler. Should, however, the boiler pressure not exceed the maximum pressure requisite for the boiling by a considerable amount, or should it, indeed, sometimes sink below this pressure, the pressure medium has to be taken from another pressure receptacle. If it is then desired to employ steam as a pressure medium, the

arrangement shown in Fig. 2 may be used to advanta e. a

P is the one battery which is built for instance for a pressure of 6 kilogrammes, whereas the digesters K and K are started for example to a maximum pressure of 5.5 kilogrammes. It is now supposed that the di ester K, for the time being is steamed through the piping L while the digester K is boiling through the pi ing L' and that the pressure of the latter igester is for the moment just-5.5 kilogrammes. By the steaming the pressure in the boiler piping L, may sink for instance to 4 kilogrammes,

and there is danger in the possibility of acid finding its way from the diges't'er K through the piping L into the boilers. This is avoided b a pressure lock according to Fig. 1, which is supplied with steam from an accumulator X filled with water, the said accumulator communicating with the boiler piping L, through the non-return valve Y and the piping Z. If found suitable, a valve Q may be arranged in thepiping Z.. Thus the pressure lock or locks respectivel communicate with the steam space of he accumulator, while the water space thereof communicates with the boilfer's. Hera the accumulator is always kept charge to a pressure approaching the maximum pressure of the boilers. What I claim as new and desire to secure by Letters Patent of the United States is :i- 1. In digesters, the combination withthe steam boiler, a steam conduit, a cut-off valve and another valve, of a pressure lock consisting of a pipe opening into the said steam conduit between the said cut-off valve and the said other valve, the said pipe communicating with a pressure medium of higher pressure than themaximum pressure of the digester. V '2. In a construction as Specified in claim 1, the arrangement of the said pipe opening into the said steam conduit between the cutofl" valve and a non-return valve.

3. In a construction as specified in claim 1, the arrangement of the said pipe communicating with steam of higher pressure than the maximum pressure of the digester.

4. In a. construction as specified in claim 1, the arrangement of a connecting pipe between the said tWo valves, the said connecting pipe being vertically arranged for the purpose of producing a liquid seal.

5. In a construction as specified in claim lator.

In testimony whereof I afiix my signature in presence of two wltnesses.

J OHANNES KARL RUTHS.

Witnesses FRITZ E. HALLIN, P. H. BERGROTH. 

